Transcript Introduction (P. Migliozzi) - Slides

Introduction
Status of the ongoing analyses
 Brick finding
 Electron identification
 Hadron interactions
Brick finding efficiency
(D.Autiero, J.Favier, C.Heritier)


Systematic comparison of existing
algorithms
Modular integration (in progress) of


NN (specialized for classes of events), tracking
plus vertexing and muonID in a combined 3D
brick finding algo. (output 3D probability map)
Definition of CS extraction strategy on the
basis of the 3D map
 final brick finding efficiency and scanning load
Electron identification
in an OPERA brick
(L.S. Esposito and PM in the year 2000)




Eff. for shower followed in
36 films (6.4 ~X0)

EM and hadronic showers
simulated in an OPERA brick
No background simulation but
all other effects
Analysis based on neural
network (SNNS software
package)
In the range (215 GeV) and
for particle followed at the
least for 2.5 X0, eID and pID is
~ 99%
Energy resolutions about
30%/E(GeV)
Simulations of electrons
in a brick of OPERA
(Y. Caffari, L. Chaussard)
5000 e- (1 GeV to 10 GeV)
placed in the middle and in
front of the first emulsion
• last OpRoot geometry (BRICK.C)
• simulation with VMC – GEANT3
• hits only (no digitization)
physical processes :
• cut on the electron energy : 1 MeV
• cut on the photon energy : 1 MeV
• default GEANT3 physical processes
(Compton effect, bremsstrahlung, pair creation...)
Views of electromagnetic
showers : 1 GeV and 5 GeV
Mean radius of the
electromagnetic shower vs
emulsion number
mean radius (cm) 1 GeV
rMolière ~ 1.8 cm
5 GeV
10 GeV
emulsion number
Hits transverse dispersion
5 GeV
x (cm)
1 GeV
10 GeV
Emulsion number
Estimate of the electron energy
• number of microtracks in the shower
• multiple scattering : coordinate method
• multiple scattering : angular method
• shape of the electromagnetic cascade (e.g. mean radius)
neural network ?
Next step
• insertion of microtrack (in)efficiencies (angular cuts, ...)
• measurement of the electron energy from multiple scattering
at the beginning of the shower, and combination of methods
(neural net ?)
• simulation of electrons randomly in the whole brick
• simulations with severals electrons in one brick
• introduction of noises (cosmics rays, hadronic shower,...)
• use of the TT information
Study of hadronic interactions

Hadronic interactions



Very dangerous background! Geant MC not able
to describe the few available data
For the Proposal we used FLUKA standalone
We have now two independent MC: FLUKA and
GEANT4: a comparison is being performed by
M.Hauger, M.Sioli, L.S.Esposito, J.Damet,
F.Juget, I.Janicsko
Preliminary results
GEANT4
FLUKA
Pt > 250 MeV
Pdau > 1 GeV
no g escaping Pb
p energy
Pt > 600 MeV
Pdau > 2 GeV
no g escaping Pb

Data from CHORUS
presented by U. Kose
@CHORUS Meeting
Decay Topologies
Kink
31
Vee
71
Trident
43
4Vee
21
and 1 event with “D-zero 2ry interaction??”
Secondary interactions
1/7 of the statistics
Neutral
Charged
Ns/
Nh
1
0
1
3
1
1
1
2
4
5
6
1
1
3
1
4
1
1
8
10
12
1
1
Ns/
Nh
0
1
2
3
1
1
1
4
1
5
5
6
9
1
1
2
3
1
1
The study with FLUKA is in
progress in Naples
What do we need to exploit
the OPERA sensitivity?




Basic quantities for physics analysis
CNGS monitoring (not important for near
future development), but already discussed
in the proposal
General interest processes
Physics analysis
CNGS monitoring

Paper from LVD Coll. (hep-ex/0304018) on the CNGS
monitoring





From the abstract “The importance of an adequate CNGS beam
monitor at the LNGS has been stressed in many papers …”
From the paper, no mention at all about preliminary results we
quoted in the Proposal
OPERA has enough mass and a muon spectrometer (unique
feature)
In order to avoid confusion (i.e. in the past the lack of
information generated the conviction that OPERA was not
able to identify electrons!!!), I would propose that a small
group of people study this aspect.
Non negligible “drawback” of this study could be a
publication
Next meeting
We are planning to have a Physics
Coordination meeting (together
with the Software) by mid of
July to discuss the status of the
efficiency calculation